Hi Dmitry, our DB is not really huge. It was enough to rise the mysql package size to 64M ;) Renaming the sub-wiki to "xwiki" didn't worked for me. I've got this StackOverflow: java.lang.StackOverflowError: null at java.util.regex.Pattern$Slice.match(Pattern.java:3496) ~[na:1.6.0_18] at java.util.regex.Pattern$Start.match(Pattern.java:3072) ~[na:1.6.0_18] at java.util.regex.Matcher.search(Matcher.java:1116) ~[na:1.6.0_18] at java.util.regex.Matcher.find(Matcher.java:552) ~[na:1.6.0_18] at java.util.regex.Matcher.replaceAll(Matcher.java:819) ~[na:1.6.0_18] at java.lang.String.replace(String.java:2219) ~[na:1.6.0_18] at org.xwiki.model.internal.reference.DefaultStringEntityReferenceSerializer.serializeEntityReference(DefaultStringEntityReferenceSerializer.java:65) ~[xwiki-platform-model-4.4.jar:na] at org.xwiki.model.internal.reference.AbstractStringEntityReferenceSerializer.serialize(AbstractStringEntityReferenceSerializer.java:44) ~[xwiki-platform-model-4.4.jar:na] at org.xwiki.model.internal.reference.AbstractStringEntityReferenceSerializer.serialize(AbstractStringEntityReferenceSerializer.java:32) ~[xwiki-platform-model-4.4.jar:na] at com.xpn.xwiki.user.impl.xwiki.XWikiRightServiceImpl.checkRight(XWikiRightServiceImpl.java:326) ~[xwiki-platform-legacy-oldcore-4.4.jar:na] at com.xpn.xwiki.user.impl.xwiki.XWikiRightServiceImpl.checkRight(XWikiRightServiceImpl.java:442) ~[xwiki-platform-legacy-oldcore-4.4.jar:na] I figured it out that the XWiki.XWikiAllGroup caused the problem. Maybe some rights or users from the main wiki, i'm not sure about that. But yes, XEM is nice to manage multiple wikis, and our project will benefit of XEM. But we have some serve problems with XEM: see this thread: http://xwiki.475771.n2.nabble.com/severe-trouble-with-web-crawlers-tp7442162... Currently im working with partial space exports / imports. But its hard to get only the pages which not leave the xwiki in a unrecoverable state (with the exception). Greetings Jan -- View this message in context: http://xwiki.475771.n2.nabble.com/Converting-XEM-to-XE-with-specific-subwiki... Sent from the XWiki- Users mailing list archive at Nabble.com.